The present invention relates to underground storage of water and more specifically to a system and method which directs water to underground storage zones having available storage capacity. The presently disclosed system and method further may be directed toward water storage in land where the land surface is utilized for other purposes, such as for agricultural use, thereby making efficient use of the land by allowing the concurrent use of the surface and subsurface.
In the face of growing demand for water and the statutory and regulatory framework which address groundwater sustainability, industries which rely on groundwater, especially agriculture, recognize the need to increase surface water imports and expand underground water storage capacity. Underground water storage reservoirs provide an alternative to storage of water in open reservoirs. Underground water storage reservoirs, i.e., aquifers, will have one or more porous and permeable layers. Porosity and permeability are the aquifer properties which, respectively, refer to the pore volume available for water storage and the hydraulic conductivity of the aquifer. For utilization for underground water storage, an underground zone must have available pore space and water must be able to flow through the zone to be recovered for utilization for irrigation or other use.
Groundwater recharge is a water management tool by which surplus surface water supplies are stored underground for later recovery during periods of reduced water supply. Recharge reduces or eliminates the need to construct costly surface reservoirs which are prone to excessive evaporation losses, particularly in and climates in the Western United States. With heavy rain or snow fall, water must be released from surface reservoirs must be released to make room for inflow. Recharge has the added benefit of improving water quality by filtration through underlying sediments.
In general, if farmers and municipalities and quasi-municipalities, such as water districts, irrigation districts and water storage districts (collectively “water districts”) are able to conserve water and bank some of their allocation, they will be able to reclaim it later, either for their own use or for sale. In programs offered by some water districts, incentives are offered to private landowners to provide groundwater recharge facilities for banking surplus water for future extraction. These programs typically anticipate that water will be delivered to the private recharge facilities through district-owned distribution systems and that the water will be introduced into the underground reservoir by surface recharge basins. However, the water district may also store surface water for others within district-owned recharge facilities and the water district receive benefit for storing the groundwater.
The surface recharge basins are typically required to be open, unfarmed, fallow land. The point of delivery from the water district to a private banking and recharge facility is typically district owned metered turnout, with the landowner assuming all responsibility and liability for the water after the point of delivery. Because of this assumption of liability, control and protection of the water is a significant factor in the design of a recharge facility.
With these policies in place, it is desirable to develop additional underground storage for groundwater. It is also important to be able diminish water loss through evaporation, to determine where the water is going and how much storage capacity remains and, in some cases, to receive alarms when a particular aquifer is full and ground water is approaching the surface so that water may be directed to alternative water storage facilities. In addition, the incentives offered by the above-described programs typically credit the owner of the banking and recharge facility with a “banked water account credit” which is a percentage of the water banked in the facility. While the transferability and fungibility of these credits is evolving throughout the country with the development of sustainable groundwater policies, in general the credits are a valuable asset realized by owners of groundwater recharge facilities, and a method which facilitates obtaining such credits is desirable.
As opposed to surface recharge basins, some recharge facilities introduce the water into the underground reservoir by piping systems. This type of system expedites introduction of the water into the aquifer and thereby reduces evaporation losses. However, depending upon the design of the water storage facility, the underground reservoir may still require the dedication of significant areas of real property. Moreover, such systems do not, without additional control mechanisms or structure, identify the particular zones or depth into which the water is introduced. Identifying the zones or depth into the water is introduced can be a significant issue if the underground water storage facility is beneath a land surface utilized for agricultural purposes because saturation of the root-zone can be detrimental to the health of a crop.